DESCRIPTION: The purpose of this study is to develop age-related performance norms for a test for use by rehabilitation specialists to diagnose delayed motor performance in infants at risk for developmental disability. The Test of Infant Motor Performance (TIMP) is used to assess postural control needed by infants from 34 weeks postconceptional age (PCA) to 4 months past term-equivalent age to change positions, orient to stimuli, and interact with the environment. Previous work demonstrated the test's sensitivity to maturation, medical complications, and physical therapy. Test-retest stability over 2 to 3 days is .89, and concurrent validity at 3 mo. of age has been documented with a test with predictive validity to 18-month neurologic outcome. Demands placed on infants in the TIMP reflect the demands for movement infants experience in naturalistic interactions with caregivers. A short version of the test (Tailored Test, TT) acts as a screening tool. Performance on both the TIMP and the TT will be assessed in 1200 infants in 12 nursery settings in order to develop norms for 12 different ages (2-wk. ranges). The sampling frame will represent ethnic diversity in the national high risk infant population and reflect the distribution of risk for disability. Means, standard deviations, and percentile ranks for performance of 12 age groups will be derived and standardized measures for the entire range of performance on the test will be developed from a Rasch analysis of the data, yielding an interval-scale. A test form for use by clinicians will be developed based on comparison of raw score performance to Rasch measures in order to allow therapists to derive an estimated standardized measure from raw score performance in a clinical setting. A receiver operating characteristics curve will be used to provide information on score cutoffs at each age on the TIMP TT that correspond to 2 standard deviations below the mean on the full lIMP test in order to provide information to therapists regarding TT scores that suggest the need for a diagnostic evaluation using the full assessment. Following completion of this project, the TIMP will be available for use by therapists to diagnosis motor developmental delay in infants from 34 weeks PCA to 4 months past term.